1. Field of the Invention
The present invention generally relates to a cylinder intake air quantity determination device for an internal combustion engine. More specifically, the present invention relates to a cylinder intake air quantity determination device that is configured and arranged to calculate a cylinder intake air quantity with good precision based on a manifold internal pressure and a cylinder internal pressure.
2. Background Information
Japanese Laid-Open Patent Publication No. 2001-50091 discloses a cylinder intake air quantity determination device for a variable valve timing control internal combustion engine. The cylinder intake air quantity determination device disclosed in this reference is configured to calculate an amount of air inside an intake manifold by computing a balance between an amount of air flowing into the intake manifold and an amount of air flowing out of the intake manifold which corresponds to a cylinder intake air quantity flowing from the manifold to the cylinder computed in a previous control routine. Then, the cylinder intake air quantity determination device of this reference is configured to compute a current cylinder intake air quantity based on the amount of air inside the manifold and a cylinder volume that is corrected based on a volume of the cylinder when an intake valve is closed.
Japanese Laid-Open Patent Publication No. 2002-371894 discloses another example of a cylinder intake air quantity determination device for an internal combustion engine. In this reference, a mass air quantity inside an intake manifold is calculated by computing a balance between an amount of air flowing into the intake manifold and an amount of air flowing out of the intake manifold. Then, a cylinder intake mass air quantity flowing into a cylinder is calculated. Moreover, in the cylinder intake air quantity determination device disclosed in this reference, the mass air quantity inside the intake manifold is corrected to remove a superfluous air amount to obtain a mass air quantity inside the intake manifold when the engine is stopped. Then, this corrected mass air quantity inside the intake manifold is used to calculate an initial value for a mass air quantity inside the intake manifold when the engine is restarted.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved cylinder intake air quantity determination device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.